The disclosed apparatus relates with particularity to Ser. No. 844,520 filed on even date herewith and is assigned to the common assignee and the disclosure thereof is hereby incorporated by reference. The incorporated subject matter sets forth a modular document printing system which comprises a document feeder module, one or more document printing modules and a document receiver module coupled together to form an integrated printing system. The document printing modules include print heads which can print sequential numeric information, constant numeric information and alphanumeric information. The printing can be performed in machine readable form and each of the printing modules prints in a preselected location on a document passing therethrough. A large number of different printing formats is attainable by assembling a plurality of printing modules of different types.
The instant apparatus can be incorporated into each of the printing modules such that a determination to print on a document or inhibit printing on a document can be made according to the presence or absence of a recognizable code on the document. An example of an application of the instant apparatus within the modular document printing system is where a succession of a first type of document is being consecutively numbered by a printing module. If, within the succession, it is required to intersperse one or more of a second type of document which is not to be sequentially numbered, it is merely required that these interspersed documents be provided with a recognizable print inhibit code so that the consecutive numbering printing module will not print on these documents. This permits more of the first type of document to follow the interspersed documents without interruption of the numerical sequence. It can be seen that providing such a print inhibiting apparatus within each printing module enables the modular document printing system to be more flexible in its application.